Preparation Of Amphiphilic Block Copolymer And Its Application In Anti-Fogging And Anti-icing

As a smart material,temperature-sensitive hydrogel can respond to temperature stimuli and has important potential application in many fields.The thermal response temperature of temperature-sensitive hydrogel materials is a key performance indicator of this type of material.Limited by the freezing temperature of water,it is a challenge to broaden the sol-gel transition temperature of temperature-sensitive hydrogels below the freezing temperature.This thesis aims to synthesize a hydrogel with an adjustable temperature-sensitive phase transition temperature and explore its performance as an anti-fogging and anti-icing material.The following research content is carried out.1.Using reversible addition-fragmentation chain transfer(RAFT)polymerization method,the hydrophilic end block PDMAA(poly-N,Ndimethylacrylamide),and the hydrophobic middle part PDAAM(polydiacetone acrylamide)(PDMAA-b-PDAAM-b-PDMAA)is synthesized.The RAFT chain transfer agent with double leaving groups is used in the synthesis,and the amphiphilic ABA segment structure polymer is synthesized through a one-pot two-step polymerization process.Based on the self-assembly characteristics of the amphiphilic polymer,low-temperature spherical particles and hightemperature worm structures,and give the material a temperature-sensitive hydrogel with a low critical dissolution temperature.The chain length,the influence of pH value,concentration,blend composition and other factors on the temperature-sensitive phase transition temperature(Tgel)enables precise control of Tgel in the range of-10℃ to 45℃.2.Select the block copolymer hydrogel with Tgel higher than 4℃ to prepare a coating with excellent anti-fogging performance.The thickness of the coating is about 100 μm.The surface of the coating is in good condition after drying.The visible light transmittance in the 400-800 nm band is relatively high.As the degree of polymerization of the hydrophobic block of PDAAM increases,the light transmittance of the coating first increases and then decreases.The lowest light transmittance is still higher than 70%,and the highest light transmittance is close to 100%and is comparable to that of the empty glass.The excellent antifogging performance of the coating is verified by the hot steam method.The coating still maintains a high light transmittance under a hot steam environment of up to 1800 s,and the hot steam can also repair defects such as scratches in the coating,so that the coating has self-healing properties.3.The block copolymer hydrogel with Tgel lower than 0℃ was selected,and the ice control performance of the hydrogel was studied.The non-freezing bound water content in the system shows an increasing trend with the increase of the length of the hydrophobic chain segment,and the copolymer coating can significantly delay the time when the water droplets begin to crystallize on the surface.The copolymer exhibits significant water recrystallization inhibitory activity in the aqueous dispersion.The average maximum grain size(MLGS)measured during the recrystallization process gradually decreases with the decrease of the Tgel,from 3656 μm2 of pure water to 209 μm2.When the block copolymer transforms from gel to sol in the temperature range below the freezing point,a slip layer can be formed on the surface of the substrate and ice particles,which has potential application prospects in deicing materials.